The developments in Web 2.0 and other software has made it easier than ever to create your own digital content.

Basics:
Turn your Powerpoints and Keynote presentations into "podcasts" by saving the slides as jpegs. These can be put onto mobile devices and viewed as a "slideshow". Keynote (Mac) also allows you to export your presentation as a podcast to itunes, then upload to your device.
To create presentations with a bit of a difference http://www.prezi.com

Screen capture:

http://wisdom-soft.com/products/screenhunter_free.htm

Screen Hunter - great little program, but the files can be large.

http://www.jingproject.com/

Jing - creates FLV files, which can be saved to your computer, inserted in any number of sites.
You can create images with annotations as well as videos.

Audio Capture/Podcasts/Vodcasts

Audacity - http://audacity.sourceforge.net/

Garageband - Mac
Moviemaker and iMovie
Flip camera
Mobile phone
iPod video capture
uStream http://www.ustream.tv/
Wobook http://www.wobook.com/

Creating Games

http://classtools.net/ online game creator

SCORM http://en.wikipedia.org/wiki/Scorm
eXe Learning : http://sourceforge.net/apps/trac/exe/wiki
Hot Potatoes: http://hotpot.uvic.ca/

SCORM creations are easily uploaded to Moodle